How to Translate All These Objects At Once?
you can select them one by one in the "outliner" (not layers) by Shift clicking on each object's name, one by one.
or you can go to the 3d View where your objects are and press A once or twice to select them all.  

To move them to the origin (0,0,0 at the center of the 3d view) , first press shiftc to make the cursor go to the origin.
then (while the objects still all selected ) press shiftS , and choose selected to 3d cursor.